<!DOCTYPE html>
<html lang="en-US">
  <head>
    <meta charset="utf-8">
    <meta name="viewport" content="width=device-width,initial-scale=1">
    <title>Denzel - DIY系列</title>
    <meta name="description" content="前端笔记">
    <meta name="keywords" content="web前端,HTML5,CSS3,Javascript,SVG,canvas">
  <meta name="anthor" content="Denzel">
  <meta name="theme-color" content="#3eaf7c">
  <meta name="apple-mobile-web-app-capable" content="yes">
  <meta name="apple-mobile-web-app-status-bar-style" content="black">
  <meta name="msapplication-TileImage" content="/icons/msapplication-icon-144x144.png">
  <meta name="msapplication-TileColor" content="#000000">
  <link rel="icon" href="/blog/vuepress/logo.png">
  <link rel="manifest" href="/blog/vuepress/manifest.json">
  <link rel="apple-touch-icon" href="/blog/vuepress/icons/apple-touch-icon-152x152.png">
  <link rel="mask-icon" href="/blog/vuepress/icons/safari-pinned-tab.svg" color="#3eaf7c">
    
    <link rel="preload" href="/blog/vuepress/assets/css/0.styles.d4f29607.css" as="style"><link rel="preload" href="/blog/vuepress/assets/js/app.15770e34.js" as="script"><link rel="preload" href="/blog/vuepress/assets/js/13.1e0cf594.js" as="script"><link rel="prefetch" href="/blog/vuepress/assets/js/46.59c0ece7.js"><link rel="prefetch" href="/blog/vuepress/assets/js/1.05e4270f.js"><link rel="prefetch" href="/blog/vuepress/assets/js/2.ace739f7.js"><link rel="prefetch" href="/blog/vuepress/assets/js/3.636e5a79.js"><link rel="prefetch" href="/blog/vuepress/assets/js/4.7a55aa4b.js"><link rel="prefetch" href="/blog/vuepress/assets/js/5.b56b0573.js"><link rel="prefetch" href="/blog/vuepress/assets/js/6.e9a3fbc8.js"><link rel="prefetch" href="/blog/vuepress/assets/js/7.aa46c47d.js"><link rel="prefetch" href="/blog/vuepress/assets/js/8.a9288ac6.js"><link rel="prefetch" href="/blog/vuepress/assets/js/9.b9f8dec6.js"><link rel="prefetch" href="/blog/vuepress/assets/js/10.3e2ea470.js"><link rel="prefetch" href="/blog/vuepress/assets/js/11.4d115f98.js"><link rel="prefetch" href="/blog/vuepress/assets/js/12.c97cf4d0.js"><link rel="prefetch" href="/blog/vuepress/assets/js/14.bab9026a.js"><link rel="prefetch" href="/blog/vuepress/assets/js/15.1a24cffe.js"><link rel="prefetch" href="/blog/vuepress/assets/js/16.e9995850.js"><link rel="prefetch" href="/blog/vuepress/assets/js/17.86a1f7d2.js"><link rel="prefetch" href="/blog/vuepress/assets/js/18.c32400c4.js"><link rel="prefetch" href="/blog/vuepress/assets/js/19.9f99887c.js"><link rel="prefetch" href="/blog/vuepress/assets/js/20.82f0c2f9.js"><link rel="prefetch" href="/blog/vuepress/assets/js/21.7f5c223d.js"><link rel="prefetch" href="/blog/vuepress/assets/js/22.acf9934c.js"><link rel="prefetch" href="/blog/vuepress/assets/js/23.20d8e817.js"><link rel="prefetch" href="/blog/vuepress/assets/js/24.acf27379.js"><link rel="prefetch" href="/blog/vuepress/assets/js/25.20165510.js"><link rel="prefetch" href="/blog/vuepress/assets/js/26.83a2ddc3.js"><link rel="prefetch" href="/blog/vuepress/assets/js/27.33276a04.js"><link rel="prefetch" href="/blog/vuepress/assets/js/28.e320efab.js"><link rel="prefetch" href="/blog/vuepress/assets/js/29.3fd92c30.js"><link rel="prefetch" href="/blog/vuepress/assets/js/30.2bc84d43.js"><link rel="prefetch" href="/blog/vuepress/assets/js/31.d70ed500.js"><link rel="prefetch" href="/blog/vuepress/assets/js/32.e7a0f8e1.js"><link rel="prefetch" href="/blog/vuepress/assets/js/33.c48ee70b.js"><link rel="prefetch" href="/blog/vuepress/assets/js/34.8ad03d1b.js"><link rel="prefetch" href="/blog/vuepress/assets/js/35.5bdb3994.js"><link rel="prefetch" href="/blog/vuepress/assets/js/36.a25f926e.js"><link rel="prefetch" href="/blog/vuepress/assets/js/37.7515cfbb.js"><link rel="prefetch" href="/blog/vuepress/assets/js/38.99347371.js"><link rel="prefetch" href="/blog/vuepress/assets/js/39.3481fc62.js"><link rel="prefetch" href="/blog/vuepress/assets/js/40.bc709734.js"><link rel="prefetch" href="/blog/vuepress/assets/js/41.e1e0a3bf.js"><link rel="prefetch" href="/blog/vuepress/assets/js/42.762b61b0.js"><link rel="prefetch" href="/blog/vuepress/assets/js/43.8f0b2d6c.js"><link rel="prefetch" href="/blog/vuepress/assets/js/44.2a0a4ee0.js"><link rel="prefetch" href="/blog/vuepress/assets/js/45.baf7ed60.js"><link rel="prefetch" href="/blog/vuepress/assets/js/47.11a8720a.js"><link rel="prefetch" href="/blog/vuepress/assets/js/48.e0bf8b54.js"><link rel="prefetch" href="/blog/vuepress/assets/js/49.c96c4011.js"><link rel="prefetch" href="/blog/vuepress/assets/js/50.31189263.js"><link rel="prefetch" href="/blog/vuepress/assets/js/51.766a8294.js"><link rel="prefetch" href="/blog/vuepress/assets/js/52.26b971fd.js"><link rel="prefetch" href="/blog/vuepress/assets/js/53.0cfbd708.js"><link rel="prefetch" href="/blog/vuepress/assets/js/54.bdc15c87.js"><link rel="prefetch" href="/blog/vuepress/assets/js/55.fea285a9.js"><link rel="prefetch" href="/blog/vuepress/assets/js/56.e030a6b2.js"><link rel="prefetch" href="/blog/vuepress/assets/js/57.bd168a1e.js"><link rel="prefetch" href="/blog/vuepress/assets/js/58.636557fa.js"><link rel="prefetch" href="/blog/vuepress/assets/js/59.5d1d0ce6.js"><link rel="prefetch" href="/blog/vuepress/assets/js/60.0b779f92.js"><link rel="prefetch" href="/blog/vuepress/assets/js/61.4ec3f2eb.js"><link rel="prefetch" href="/blog/vuepress/assets/js/62.8f70f114.js"><link rel="prefetch" href="/blog/vuepress/assets/js/63.9ac2b61d.js"><link rel="prefetch" href="/blog/vuepress/assets/js/64.c028fad5.js"><link rel="prefetch" href="/blog/vuepress/assets/js/65.923a8d15.js"><link rel="prefetch" href="/blog/vuepress/assets/js/66.73db652e.js"><link rel="prefetch" href="/blog/vuepress/assets/js/67.1a91446d.js"><link rel="prefetch" href="/blog/vuepress/assets/js/68.e5a12a42.js"><link rel="prefetch" href="/blog/vuepress/assets/js/69.6ddcb882.js"><link rel="prefetch" href="/blog/vuepress/assets/js/70.ceb70d85.js"><link rel="prefetch" href="/blog/vuepress/assets/js/71.a804ef40.js"><link rel="prefetch" href="/blog/vuepress/assets/js/72.f1c4098c.js"><link rel="prefetch" href="/blog/vuepress/assets/js/73.2f28b842.js"><link rel="prefetch" href="/blog/vuepress/assets/js/74.571c2ab1.js"><link rel="prefetch" href="/blog/vuepress/assets/js/75.f365c2a1.js"><link rel="prefetch" href="/blog/vuepress/assets/js/76.0916a3cd.js"><link rel="prefetch" href="/blog/vuepress/assets/js/77.469aed17.js"><link rel="prefetch" href="/blog/vuepress/assets/js/78.02cdd59d.js"><link rel="prefetch" href="/blog/vuepress/assets/js/79.44d7f95c.js"><link rel="prefetch" href="/blog/vuepress/assets/js/80.4ca072f1.js"><link rel="prefetch" href="/blog/vuepress/assets/js/81.d9239a49.js"><link rel="prefetch" href="/blog/vuepress/assets/js/82.b09096b2.js"><link rel="prefetch" href="/blog/vuepress/assets/js/83.f4bc8a9b.js"><link rel="prefetch" href="/blog/vuepress/assets/js/84.1ffe6969.js"><link rel="prefetch" href="/blog/vuepress/assets/js/85.44e980f9.js"><link rel="prefetch" href="/blog/vuepress/assets/js/86.c8579ac0.js"><link rel="prefetch" href="/blog/vuepress/assets/js/87.cd49f324.js"><link rel="prefetch" href="/blog/vuepress/assets/js/88.3851b6ff.js"><link rel="prefetch" href="/blog/vuepress/assets/js/89.b05297be.js"><link rel="prefetch" href="/blog/vuepress/assets/js/90.c1e3263e.js"><link rel="prefetch" href="/blog/vuepress/assets/js/91.b493a1bb.js"><link rel="prefetch" href="/blog/vuepress/assets/js/92.80ab06fd.js"><link rel="prefetch" href="/blog/vuepress/assets/js/93.c6ca00b3.js"><link rel="prefetch" href="/blog/vuepress/assets/js/94.e993d310.js"><link rel="prefetch" href="/blog/vuepress/assets/js/95.8e19a7ed.js">
    <link rel="stylesheet" href="/blog/vuepress/assets/css/0.styles.d4f29607.css">
  </head>
  <body>
    <div id="app" data-server-rendered="true"><div class="theme-container"><header class="navbar"><div class="sidebar-button"><svg xmlns="http://www.w3.org/2000/svg" aria-hidden="true" role="img" viewBox="0 0 448 512" class="icon"><path fill="currentColor" d="M436 124H12c-6.627 0-12-5.373-12-12V80c0-6.627 5.373-12 12-12h424c6.627 0 12 5.373 12 12v32c0 6.627-5.373 12-12 12zm0 160H12c-6.627 0-12-5.373-12-12v-32c0-6.627 5.373-12 12-12h424c6.627 0 12 5.373 12 12v32c0 6.627-5.373 12-12 12zm0 160H12c-6.627 0-12-5.373-12-12v-32c0-6.627 5.373-12 12-12h424c6.627 0 12 5.373 12 12v32c0 6.627-5.373 12-12 12z"></path></svg></div><a href="/blog/vuepress/" class="home-link router-link-active"><img src="/blog/vuepress/hero.png" class="logo"><span class="site-name can-hide">
      Denzel
    </span></a><div class="links"><div class="search-box"><input aria-label="Search" autocomplete="off" spellcheck="false" value=""><!----></div><nav class="nav-links can-hide"><div class="nav-item"><a href="/blog/vuepress/js/" class="nav-link">JS</a></div><div class="nav-item"><a href="/blog/vuepress/css/" class="nav-link">CSS</a></div><div class="nav-item"><a href="/blog/vuepress/html/" class="nav-link">HTML</a></div><div class="nav-item"><a href="/blog/vuepress/else/" class="nav-link">其他</a></div><div class="nav-item"><a href="/blog/vuepress/study/" class="nav-link router-link-active">study</a></div><a href="https://github.com/xiaotianxia" target="_blank" rel="noopener noreferrer" class="repo-link">
    GitHub
    <svg xmlns="http://www.w3.org/2000/svg" aria-hidden="true" x="0px" y="0px" viewBox="0 0 100 100" width="15" height="15" class="icon outbound"><path fill="currentColor" d="M18.8,85.1h56l0,0c2.2,0,4-1.8,4-4v-32h-8v28h-48v-48h28v-8h-32l0,0c-2.2,0-4,1.8-4,4v56C14.8,83.3,16.6,85.1,18.8,85.1z"></path><polygon fill="currentColor" points="45.7,48.7 51.3,54.3 77.2,28.5 77.2,37.2 85.2,37.2 85.2,14.9 62.8,14.9 62.8,22.9 71.5,22.9"></polygon></svg></a></nav></div></header><div class="sidebar-mask"></div><div class="sidebar"><nav class="nav-links"><div class="nav-item"><a href="/blog/vuepress/js/" class="nav-link">JS</a></div><div class="nav-item"><a href="/blog/vuepress/css/" class="nav-link">CSS</a></div><div class="nav-item"><a href="/blog/vuepress/html/" class="nav-link">HTML</a></div><div class="nav-item"><a href="/blog/vuepress/else/" class="nav-link">其他</a></div><div class="nav-item"><a href="/blog/vuepress/study/" class="nav-link router-link-active">study</a></div><a href="https://github.com/xiaotianxia" target="_blank" rel="noopener noreferrer" class="repo-link">
    GitHub
    <svg xmlns="http://www.w3.org/2000/svg" aria-hidden="true" x="0px" y="0px" viewBox="0 0 100 100" width="15" height="15" class="icon outbound"><path fill="currentColor" d="M18.8,85.1h56l0,0c2.2,0,4-1.8,4-4v-32h-8v28h-48v-48h28v-8h-32l0,0c-2.2,0-4,1.8-4,4v56C14.8,83.3,16.6,85.1,18.8,85.1z"></path><polygon fill="currentColor" points="45.7,48.7 51.3,54.3 77.2,28.5 77.2,37.2 85.2,37.2 85.2,14.9 62.8,14.9 62.8,22.9 71.5,22.9"></polygon></svg></a></nav><ul class="sidebar-links"><li><div class="sidebar-group first collapsable"><p class="sidebar-heading open"><span>study</span><span class="arrow down"></span></p><ul class="sidebar-group-items"><li><a href="/blog/vuepress/study/" class="sidebar-link">标签</a></li><li><a href="/blog/vuepress/study/DOM.html" class="sidebar-link">DOM</a></li><li><a href="/blog/vuepress/study/js_A.html" class="sidebar-link">js A</a></li><li><a href="/blog/vuepress/study/js_AA.html" class="sidebar-link">js AA</a></li><li><a href="/blog/vuepress/study/js_AAA.html" class="sidebar-link">js AAA</a></li><li><a href="/blog/vuepress/study/css_A.html" class="sidebar-link">CSS A</a></li><li><a href="/blog/vuepress/study/css_AA.html" class="sidebar-link">CSS AA</a></li><li><a href="/blog/vuepress/study/css_AAA.html" class="sidebar-link">CSS AAA</a></li><li><a href="/blog/vuepress/study/performance.html" class="sidebar-link">性能</a></li><li><a href="/blog/vuepress/study/vue.html" class="sidebar-link">vue</a></li><li><a href="/blog/vuepress/study/vue_code.html" class="sidebar-link">vue code</a></li><li><a href="/blog/vuepress/study/algorithm.html" class="sidebar-link">算法</a></li><li><a href="/blog/vuepress/study/webpack.html" class="sidebar-link">webpack</a></li><li><a href="/blog/vuepress/study/es6.html" class="sidebar-link">es6</a></li><li><a href="/blog/vuepress/study/questions.html" class="sidebar-link">问题</a></li><li><a href="/blog/vuepress/study/mobile.html" class="sidebar-link">移动端</a></li><li><a href="/blog/vuepress/study/http.html" class="sidebar-link">http</a></li><li><a href="/blog/vuepress/study/diy.html" class="active sidebar-link">DIY系列</a></li><li><a href="/blog/vuepress/study/api.html" class="sidebar-link">API</a></li><li><a href="/blog/vuepress/study/browser.html" class="sidebar-link">浏览器原理</a></li><li><a href="/blog/vuepress/study/conception.html" class="sidebar-link">概念</a></li><li><a href="/blog/vuepress/study/engineering.html" class="sidebar-link">工程化</a></li></ul></div></li></ul></div><div class="page"><div class="content"><h1 id="diy系列"><a href="#diy系列" aria-hidden="true" class="header-anchor">#</a> DIY系列</h1><h2 id="call"><a href="#call" aria-hidden="true" class="header-anchor">#</a> call</h2><pre class="language-js"><code><span class="token comment">/*
** var value = 2;
** var obj = {
**     value: 1
** };
** 
** function bar(name, age) {
**     return {
**         value: this.value,
**         name: name,
**         age: age
**     }
** }
** 
** bar.call2(null); // 2
** 
** bar.call2(obj, 'kevin', 18);
// Object {
//    value: 1,
//    name: 'kevin',
//    age: 18
// }
*/</span>
Function<span class="token punctuation">.</span>prototype<span class="token punctuation">.</span><span class="token function-variable function">call2</span> <span class="token operator">=</span> <span class="token keyword">function</span> <span class="token punctuation">(</span>context<span class="token punctuation">)</span> <span class="token punctuation">{</span>
    <span class="token comment">//context undefined、null、'' -&gt; window</span>
    <span class="token comment">//context true\false -&gt; {}</span>
    context <span class="token operator">=</span> <span class="token keyword">typeof</span> context <span class="token operator">==</span> <span class="token string">'boolean'</span> <span class="token operator">?</span> <span class="token punctuation">{</span><span class="token punctuation">}</span> <span class="token punctuation">:</span> <span class="token punctuation">(</span>context <span class="token operator">?</span> <span class="token punctuation">(</span><span class="token keyword">typeof</span> context <span class="token operator">==</span> <span class="token string">'object'</span> <span class="token operator">?</span> context <span class="token punctuation">:</span> <span class="token punctuation">{</span><span class="token punctuation">}</span><span class="token punctuation">)</span> <span class="token punctuation">:</span> window<span class="token punctuation">)</span><span class="token punctuation">;</span>
    <span class="token comment">//临时方法fn，存储bar函数</span>
    context<span class="token punctuation">.</span>fn <span class="token operator">=</span> <span class="token keyword">this</span><span class="token punctuation">;</span>
    <span class="token comment">//执行该方法，参数不包括obj本身  es6写法... 也可遍历arguments获取</span>
    <span class="token keyword">var</span> result <span class="token operator">=</span> context<span class="token punctuation">.</span><span class="token function">fn</span><span class="token punctuation">(</span><span class="token operator">...</span><span class="token punctuation">[</span><span class="token operator">...</span>arguments<span class="token punctuation">]</span><span class="token punctuation">.</span><span class="token function">slice</span><span class="token punctuation">(</span><span class="token number">1</span><span class="token punctuation">)</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
    <span class="token comment">//删除该方法</span>
    <span class="token keyword">delete</span> context<span class="token punctuation">.</span>fn<span class="token punctuation">;</span>
    <span class="token comment">//返回bar的返回值</span>
    <span class="token keyword">return</span> result<span class="token punctuation">;</span>
<span class="token punctuation">}</span>
</code></pre><h2 id="apply"><a href="#apply" aria-hidden="true" class="header-anchor">#</a> apply</h2><pre class="language-js"><code><span class="token comment">//只需把fn的参数换成arr即可</span>
Function<span class="token punctuation">.</span>prototype<span class="token punctuation">.</span><span class="token function-variable function">apply2</span> <span class="token operator">=</span> <span class="token keyword">function</span> <span class="token punctuation">(</span>context<span class="token punctuation">,</span> arr<span class="token punctuation">)</span> <span class="token punctuation">{</span>
    context <span class="token operator">=</span> <span class="token keyword">typeof</span> context <span class="token operator">==</span> <span class="token string">'boolean'</span> <span class="token operator">?</span> <span class="token punctuation">{</span><span class="token punctuation">}</span> <span class="token punctuation">:</span> <span class="token punctuation">(</span>context <span class="token operator">?</span> <span class="token punctuation">(</span><span class="token keyword">typeof</span> context <span class="token operator">==</span> <span class="token string">'object'</span> <span class="token operator">?</span> context <span class="token punctuation">:</span> <span class="token punctuation">{</span><span class="token punctuation">}</span><span class="token punctuation">)</span> <span class="token punctuation">:</span> window<span class="token punctuation">)</span><span class="token punctuation">;</span>
    context<span class="token punctuation">.</span>fn <span class="token operator">=</span> <span class="token keyword">this</span><span class="token punctuation">;</span>
    <span class="token keyword">var</span> result<span class="token punctuation">;</span>
    <span class="token keyword">if</span><span class="token punctuation">(</span>arr<span class="token punctuation">)</span> <span class="token punctuation">{</span>
        result <span class="token operator">=</span> context<span class="token punctuation">.</span><span class="token function">fn</span><span class="token punctuation">(</span><span class="token operator">...</span>arr<span class="token punctuation">)</span><span class="token punctuation">;</span>
    <span class="token punctuation">}</span> <span class="token keyword">else</span> <span class="token punctuation">{</span>
        result <span class="token operator">=</span> context<span class="token punctuation">.</span><span class="token function">fn</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
    <span class="token punctuation">}</span>
    <span class="token keyword">delete</span> context<span class="token punctuation">.</span>fn<span class="token punctuation">;</span>
    <span class="token keyword">return</span> result<span class="token punctuation">;</span>
<span class="token punctuation">}</span>
</code></pre><h2 id="bind"><a href="#bind" aria-hidden="true" class="header-anchor">#</a> bind</h2><p>bind的特点：</p><ul><li>1.bind() 方法会创建一个新函数。</li><li>2.一个绑定函数也能使用new操作符创建对象：这种行为就像把原函数当成构造器。喜事的this指向实例对象，而不是context。</li></ul><pre class="language-js"><code><span class="token comment">/*
** var foo = {
**     value: 1
** };
** 
** function bar(name, age) {
**     console.log(this.value);
**     console.log(name);
**     console.log(age);
** 
** }
** 
** var bindFoo = bar.bind(foo, 'daisy');
** bindFoo('18');
** // 1
** // daisy
** // 18
** bind的时候可以传参，执行bind的时候也可以传参
*/</span>

<span class="token comment">//利用call和apply 只满足条件1</span>
Function<span class="token punctuation">.</span>prototype<span class="token punctuation">.</span><span class="token function-variable function">bind2</span> <span class="token operator">=</span> <span class="token keyword">function</span> <span class="token punctuation">(</span>context<span class="token punctuation">)</span> <span class="token punctuation">{</span>
    context <span class="token operator">=</span> <span class="token keyword">typeof</span> context <span class="token operator">==</span> <span class="token string">'boolean'</span> <span class="token operator">?</span> <span class="token punctuation">{</span><span class="token punctuation">}</span> <span class="token punctuation">:</span> <span class="token punctuation">(</span>context <span class="token operator">?</span> <span class="token punctuation">(</span><span class="token keyword">typeof</span> context <span class="token operator">==</span> <span class="token string">'object'</span> <span class="token operator">?</span> context <span class="token punctuation">:</span> <span class="token punctuation">{</span><span class="token punctuation">}</span><span class="token punctuation">)</span> <span class="token punctuation">:</span> window<span class="token punctuation">)</span><span class="token punctuation">;</span>
    <span class="token comment">//bind的时候 取 除context以外的参数</span>
    <span class="token keyword">var</span> args <span class="token operator">=</span> Array<span class="token punctuation">.</span>prototype<span class="token punctuation">.</span>slice<span class="token punctuation">.</span><span class="token function">call</span><span class="token punctuation">(</span>arguments<span class="token punctuation">,</span> <span class="token number">1</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
    <span class="token comment">//执行环境是bar</span>
    <span class="token keyword">var</span> self <span class="token operator">=</span> <span class="token keyword">this</span><span class="token punctuation">;</span>
    <span class="token keyword">return</span> <span class="token keyword">function</span> <span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token punctuation">{</span>
        <span class="token comment">//取执行bin时候的参数</span>
        <span class="token keyword">var</span> bindArgs <span class="token operator">=</span> Array<span class="token punctuation">.</span>prototype<span class="token punctuation">.</span>slice<span class="token punctuation">.</span><span class="token function">call</span><span class="token punctuation">(</span>arguments<span class="token punctuation">)</span><span class="token punctuation">;</span>
        self<span class="token punctuation">.</span><span class="token function">apply</span><span class="token punctuation">(</span>context<span class="token punctuation">,</span> args<span class="token punctuation">.</span><span class="token function">concat</span><span class="token punctuation">(</span>bindArgs<span class="token punctuation">)</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
    <span class="token punctuation">}</span>
<span class="token punctuation">}</span>
</code></pre><pre class="language-js"><code><span class="token comment">// 满足条件1 2 </span>
Function<span class="token punctuation">.</span>prototype<span class="token punctuation">.</span><span class="token function-variable function">bind2</span> <span class="token operator">=</span> <span class="token keyword">function</span> <span class="token punctuation">(</span>context<span class="token punctuation">)</span> <span class="token punctuation">{</span>

    <span class="token keyword">if</span> <span class="token punctuation">(</span><span class="token keyword">typeof</span> <span class="token keyword">this</span> <span class="token operator">!==</span> <span class="token string">&quot;function&quot;</span><span class="token punctuation">)</span> <span class="token punctuation">{</span>
      <span class="token keyword">throw</span> <span class="token keyword">new</span> <span class="token class-name">Error</span><span class="token punctuation">(</span><span class="token string">&quot;not a function - this is not callable&quot;</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
    <span class="token punctuation">}</span>

    <span class="token keyword">var</span> self <span class="token operator">=</span> <span class="token keyword">this</span><span class="token punctuation">;</span>
    <span class="token keyword">var</span> args <span class="token operator">=</span> Array<span class="token punctuation">.</span>prototype<span class="token punctuation">.</span>slice<span class="token punctuation">.</span><span class="token function">call</span><span class="token punctuation">(</span>arguments<span class="token punctuation">,</span> <span class="token number">1</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
    <span class="token comment">// 利用一个中间函数，用于继承bar，且bar不被修改原型</span>
    <span class="token keyword">var</span> <span class="token function-variable function">fNOP</span> <span class="token operator">=</span> <span class="token keyword">function</span> <span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token punctuation">{</span><span class="token punctuation">}</span><span class="token punctuation">;</span>

    <span class="token keyword">var</span> <span class="token function-variable function">fBound</span> <span class="token operator">=</span> <span class="token keyword">function</span> <span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token punctuation">{</span>
        <span class="token keyword">var</span> bindArgs <span class="token operator">=</span> Array<span class="token punctuation">.</span>prototype<span class="token punctuation">.</span>slice<span class="token punctuation">.</span><span class="token function">call</span><span class="token punctuation">(</span>arguments<span class="token punctuation">)</span><span class="token punctuation">;</span>
        self<span class="token punctuation">.</span><span class="token function">apply</span><span class="token punctuation">(</span><span class="token keyword">this</span> <span class="token keyword">instanceof</span> <span class="token class-name">fNOP</span> <span class="token operator">?</span> <span class="token keyword">this</span> <span class="token punctuation">:</span> context<span class="token punctuation">,</span> args<span class="token punctuation">.</span><span class="token function">concat</span><span class="token punctuation">(</span>bindArgs<span class="token punctuation">)</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
    <span class="token punctuation">}</span>

    fNOP<span class="token punctuation">.</span>prototype <span class="token operator">=</span> <span class="token keyword">this</span><span class="token punctuation">.</span>prototype<span class="token punctuation">;</span>
    fBound<span class="token punctuation">.</span>prototype <span class="token operator">=</span> <span class="token keyword">new</span> <span class="token class-name">fNOP</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
    <span class="token keyword">return</span> fBound<span class="token punctuation">;</span>
<span class="token punctuation">}</span>
</code></pre><p>参考
<a href="https://juejin.im/post/59e365856fb9a0450808b046" target="_blank" rel="noopener noreferrer">1</a><a href="https://jothy1023.github.io/2016/10/16/js-bind-es5-es6/" target="_blank" rel="noopener noreferrer">2</a></p><h2 id="promise"><a href="#promise" aria-hidden="true" class="header-anchor">#</a> promise</h2><p>https://juejin.im/post/5c2b34a15188257abf1d96eb
https://juejin.im/post/5a006ec351882554b836f1fd</p><p>https://github.com/Jocs/jocs.github.io/issues/7</p></div><div class="wx-wrapper" data-v-0de8a4bf><p class="wx-txt" data-v-0de8a4bf>欢迎关注</p><img src="http://pn4meizzc.bkt.clouddn.com/wxqr.png" class="wx-img" data-v-0de8a4bf></div><div class="beg-wrapper" data-v-1f1af99c><a href="javascript:;" class="btn show" data-v-1f1af99c><img src="http://pn4meizzc.bkt.clouddn.com/blogshang_log.png" data-v-1f1af99c></a><p class="shang-txt" data-v-1f1af99c>赏不赏，看您心情</p><img src="http://pn4meizzc.bkt.clouddn.com/blogWechatIMG35.jpeg" class="shangImg" data-v-1f1af99c></div><!----><div class="content page-nav"><p class="inner"><span class="prev">
        ← <a href="/blog/vuepress/study/http.html" class="prev">
          http
        </a></span><span class="next"><a href="/blog/vuepress/study/api.html">
          API
        </a> →
      </span></p></div></div></div></div>
    <script src="/blog/vuepress/assets/js/13.1e0cf594.js" defer></script><script src="/blog/vuepress/assets/js/app.15770e34.js" defer></script>
  </body>
</html>
